Abstract
BACKGROUND: Painless bloody nipple discharge is often classified as pathological due to its association with malignant lesions. However, it can also be a completely harmless condition. Rusty pipe syndrome is a rare cause of benign, self-limiting bloody nipple discharge during late pregnancy and early lactation. Given that rusty pipe syndrome is not described in conventional textbooks, we thought it would be appropriate to bring this benign disease to the notice of readers. CASE PRESENTATION: A 31-year-old G1P1 female delivered an infant with a birth weight of 3000 g via cesarean section at 39 weeks of gestation. The baby was admitted to the pediatric intensive care unit for a suspected oblique inguinal hernia. The mother had bilateral painless bloody nipple discharge when she started to express milk. A physical examination uncovered no signs of inflammation, engorgement, palpable mass, tenderness, cracks or ulcers. A breast ultrasound and cytological analysis revealed no signs of a neoplasm. Without any medical intervention, the color of the rusty milk changed from dark brown to light brown during hospitalization and finally resolved six days postpartum. CONCLUSION: Rusty pipe syndrome is a self-limiting benign condition that should be considered in the differential diagnosis of bloody nipple discharge. Awareness of this rare disease by medical professionals would be extremely beneficial for avoiding unneeded examinations and discontinuity of exclusive breastfeeding.